Browsing by Author "Adhikari, Gopal"

Northern peatlands store approximately one-third of total global terrestrial carbon (C). These peatlands were partly drained for agriculture and forestry. In drained peatland forest, beside tree stands, ground vegetation is another relevant component concerning C fluxes between the land and the atmosphere. Thus, to explore ground vegetation gross primary production (GPPGV) dynamics, its affecting factors, and impacts of the partial harvest; forest floor net exchange (NEFF) and respiration (RFF) were measured on an hourly interval with an automated closed flux chamber method were analysed. These measurements were conducted in a forestry drained peatland before (pre-harvest, 2013 – 2015) and after (post-harvest, 2016 – 2017) the partial harvest and a control area (2015 – 2017) located in southern Finland. The results showed a similar diurnal pattern of GPPGV in all three scenarios yet, with a considerably varying magnitude between these scenarios. An 83% increase in photosynthetically active radiation (PAR) was observed in 2016 followed by the harvest event. However, a markedly higher GPPGV was obtained in the year 2017 (139.04 mg CO2 m-2 h-1) a year after the partial harvest compared to the year 2016 (42.82 mg CO2 m-2 h-1), thereby indicating a delaying effect of partial harvest induced changes on productivity. A linear mixed effect model with fixed effects of treatment (control and partial harvest) and random effects of chambers further supported this result with a significant effect of partial harvest on GPPGV in 2017 as compared to 2016. Further, a strong positive correlation was found between the daily mean GPPGV and PAR. Additionally, types of vegetation and its share of projection cover (PC) also explained GPPGV variations between flux chambers. An increase in GPPGV after the partial harvest event showed that the ground vegetation can play a considerable role in the C cycle of a managed drained peatland forest beside tree stands. As expected, after the partial harvest more lights reached the ground layer altering productivity. Besides light availability, productivity also depends on the types and phenology of inhabiting vegetation. Thus, exploration and realization of the response of ground vegetation to the partial harvest induced changes may contribute to our understanding of natural regeneration and system recovery processes.